Recently, in the light of a trend toward so-called a lighter tobacco and an effect of a tobacco on health, various investigations have been undertaken around advanced nations to reduce an inflow rate (an amount to be delivered) of a smoke component through an oral cavity on smoking. One of methods important for the purpose is to improving a filter.
In the present tobacco smoke filter, a crimped fiber bundle (tow) of cellulose diacetate is usually used, and in order to improve the filtration efficiency, a tow having small degree of monofilament fineness, or a tow having the large amount to be charged of the fiber is often used. However, since these methods cause increase of the pressure drop (puff resistance), there is a limit to improvement of the filtration efficiency within the range of a practical pressure drop (puff resistance). Moreover, in the case where the filtration efficiency is increased using such a method, it is difficult to eliminate or remove only a specific component in smoke components selectively, that is, to discriminate the filtration ratio of each smoke component significantly. Therefore, since low-volatile smoke components are indiscriminately eliminated, a smoker does not obtain satisfaction while taste of the tobacco becomes light.
Therefore, until now, various materials or additives have been proposed for improvement of filterability of a filter. For example, as an additive for reducing an amount of nicotine to be delivered, nicotinic acid amide (Japanese Patent Application Laid-Open No. 216178/1991 (JP-3-216178A)), proteases (Japanese Patent Application Laid-Open No. 290176/1991 (JP-3-290176A)) and others have been proposed. Incidentally, since the delivery of tar also has become of interest, in many countries, there is duty of indication of tar content label in the same manner as nicotine. However, there is no report of a substance excellent in an ability of eliminating tar. Nicotine itself is a component imparting a taste to a tobacco, and is regarded as having a direct influence on satisfaction of smoking. From this viewpoint, it is considered that removing a tar component at relatively high level is preferred so as not to lose the aroma and palatability of the tobacco.
Japanese Patent Application Laid-Open No. 71677/1984 (JP-59-71677A) discloses a filter material for a cigarette containing a filter medium, and the filter medium is obtained by applying a filter medium, and the filter medium comprises a porous natural substance containing magnesium silicate as a main component and chestnut tannin singly, or optionally a coffee bean extract, a tea-leaf extract or a licorice extract, on a surface of that. Japanese Patent Application Laid-Open No. 115273/1993 (JP-5-115273A) discloses a tobacco obtained mixing epigallocatechingallate to the tobacco itself and the filter part. Moreover, Japanese Patent Application Laid-Open No. 23159/1993 (JP-5-23159A) discloses a tobacco filter containing ellagic acid. However, in the above-described filters, it is impossible to eliminate or remove a tar component effectively with keeping the aroma and palatability.
On the other hand, a free radical component in tobacco smoke has essentially extremely high reactivity so that there is possibility that the free radical component gives an undesirable influence on health. Therefore, the eliminating or removing of the free radical component becomes of interest, and some methods to enhance the filtration efficiency have been conducted (e.g., Japanese Patent Application Laid-Open No. 237770/1988 (JP-63-237770A)).
For example, Japanese Patent Application Laid-Open No. 248380/1988 (JP-63-248380A) proposes use of an active carbon. However, the active carbon is a superior adsorbent which adsorbs not only a free radical component but also many substances simultaneously. The aroma and palatability of a tobacco itself are remarkably deteriorated when the active carbon is used in large quantity. Moreover, it is considered that the active carbon itself gives a unique influence on the taste and palatability.
Japanese Patent Application Laid-Open No. 232371/1987 (JP-62-232371A) discloses a tobacco filter containing an amino acid such as tryptophan. However, a efficiency of eliminating a radical by the filter is low. Also, if the amino acid is burned, there is a problem that the amino acid produces a strong carcinogenic substance such as tryptophan pyrolysate P2.
Japanese Patent Application Laid-Open No. 78739/1994 (JP-6-78739A) discloses that active oxygen can be removed by using a filter in which a ginkgo-leaf extract is adhered or applied to a three-dimensional formed porous material (substance). Moreover, WO99/33365 discloses that a rosemary extract is effective for elimination of a free radical in a tobacco filter. However, since the rosemary extract comprises a relatively low-molecular-weight constitutive component, the extract has the unique aroma. Therefore, in the case where the extract is applied to an ordinary tobacco, the aroma, taste and palatability are sometimes deteriorated. Furthermore, the both extracts mentioned above are not satisfactory for an ability of eliminating a free radical component.
Chinese Patent Application Laid-Open No. 1145206A discloses a cigarette which comprises a filter containing polyphenol extracted from tea, vitamin C and an active carbon, and which is of a low free radical and a low toxicity. However, the filter is not satisfactory for an ability of capturing a radical.
Furthermore, in a conventional filter for tobacco smoke, an ability of selectively eliminating a tar component relative to a nicotine component and an ability of eliminating a free radical component are incompatible at high level with each other.
Therefore, an object of the present invention is to provide an element for tobacco smoke which is capable of eliminating a tar component selectively and a process for producing the same.
It is other object of the present invention to provide an element for tobacco smoke which is capable of eliminating a free radical component effectively and a process for producing the same.
It is still other object of the present invention provide an element for tobacco smoke in which an ability eliminating a tar component with high selectivity and an ability of highly eliminating a free radical component can be compatible with each other without deteriorating the aroma and palatability, and a process for producing the same.
It is another object of the present invention to provide a process for being capable of eliminating a tar component and/or a free radical component effectively.